1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device with uniform common voltage distribution within a display panel to provide enhanced display quality.
2. Discussion of the Related Art
As a society of information technology grows, there is a demand for development of image display devices capable of solving drawbacks of conventional cathode ray tubes (CRTs), such as weight and volume thereof. Accordingly, a variety of flat panel display devices, including liquid crystal display (LCD) devices, organic light emitting diodes (OLEDs), plasma display panel (PDP) devices, surface-conduction electron-emitter display (SED) devices, and the like, have attracted considerable attention. Of the above-mentioned display devices, the most representative flat panel display device is the LCD device, which has been widely used as a large-scale TV screen to a small display screen of a mobile phone.
LCD devices are configured with a liquid crystal material, exhibiting dielectric anisotropy and refractive index anisotropy, arranged between two electrodes. Transmission of light is adjusted by controlling the strength of an electric field generated between the two electrodes to generate a desired display image. LCD devices are not self-illuminating type display devices (i.e., displays capable of emitting light by itself) but a light-receiving type display device designed to realize an image upon receiving light from a light source situated therein.
Generally, the LCD device receives white light from a light source situated therein and generates color images using color filters, such as red, green, and blue colors. In the above-described configuration of the LCD device, the two electrodes that drive liquid crystals in the liquid crystal material generally include a pixel electrode and a common electrode. These electrodes are connected to a thin film transistor with the pixel electrode receiving a voltage corresponding to an image signal and the common electrode receiving a common voltage. The liquid crystals are driven by an electric field generated between the two electrodes. However, the above-described conventional LCD device has the following problems.
A common line, which serves to supply a common voltage to a panel of the LCD device, is horizontally formed with only one or two input terminals to apply the common voltage to the common line. Therefore, achieving uniform distribution of the common voltage in a large-scale display panel becomes difficult due to resistance in the common line, for example. This deteriorates image quality, such as causing after-images, and the like. In particular, in the case of display panels used in televisions, the common lines have longer horizontal lengths than vertical lengths. Therefore, these panels suffer from an increased resistance in the common lines. Accordingly, there is a high likelihood of wire breakage and crosstalk.